Brackets for supporting shelves inside cabinets, bookcases, and the like, while at the same time permitting the shelves to be readily adjustable, have been known for some time. However, the shipping of cabinets with internal shelves presents a problem. With shelf supports that do not also positively retain or lock the shelf in place, the jostling or shock that the article of furniture receives during shipping and handling can cause the shelf to bounce around within the cabinet and damage the cabinet. Thus, shelf supports having a retaining mechanism to maintain the shelf in position during movement have been proposed. Examples are shown in U.S. Pat. Nos. 4,666,117 to Taft; 4,432,523 to Follows; and 4,053,132 to Del Pozzo.
Even when cabinets are not shipped with shelves installed in place, it is extremely desirable to lock the shelves in place within the cabinets to prevent jostling of the shelves and the shelves from consequently falling down between the supports, and damaging the contents of any shelf positioned beneath that shelf. Thus, it is much more desirable to provide a cabinet or bookcase with an adjustable shelf that has the rigid and solid feel of a permanently installed shelf.
U.S. Pat. No. 3,471,112 to MacDonald et al. discloses a shelf support in which a resilient finger locks the shelf in place. The MacDonald device serves to reduce or prevent vertical movement of the shelf once it is installed in place. However, a problem with the MacDonald device is that no means is provided for resiliently retaining the shelf against lateral movement if the shelf is not precisely dimensioned to fit within the intended space. As will be appreciated, it is difficult to cut wood shelves to precise width dimensions so that all lateral movement of the shelf is avoided. Hence, the width of the shelves installed in a typical bookcase can vary around a median width, with some shelves being relatively long and other shelves being relatively short. Since shelves that are too wide must necessarily be trimmed to a shorter width or they will not fit into the provided space at all, the result can be shelves that rattle significantly within the cabinet of some means for cushioning lateral movement is not provided.
U.S. Pat. No. 4,037,813 to Loui et al. discloses a shelf support in which a shelf is passed over resilient members that carry a locking shoulder. The locking shoulder serves to reduce or prevent vertical movement of the shelf once it is installed in place, and the resilient members serve to tension the shelf against lateral movement. Thus, some variability of width of the shelf installed in place can be accommodated. However, this goal is frustrated in part by the need to force the shelf over the shoulder, which is formed from a solid piece that is angular in cross-section. As will be immediately apparent from FIGS. 3 and 4 of Loui, a shallower shoulder is required when a relatively long shelf is inserted, or the shelf will not be able to pass over the shoulder. However, a shallow shoulder will not effectively retain a shelf in place against jostling or the like, particularly on those occasions when a relatively short shelf is inserted in place.
Accordingly, there is a need in the art for locking shelf supports that are able to securely lock shelve in place, which can accommodate the usual variability of shelf length, and do not rely upon precise lengthwise cutting of the shelves to be installed.